The company launched its cloud-based software from Hungary in 2009 and says it now has more than 50 million users—nearly double the number it had last year—who have created more than 160 million presentations. Many of these presentations are in a public database maintained by Prezi and can be reused.

Prezi’s software is unusual because the presentations it produces aren't the usual lists of bullet points. They are based on images and require their creators to tell a story, which helps an audience absorb and remember the information, according to co-founder and Chief Executive Peter Arvai. Presenters can switch the order of slides and zoom in and out.

“[Images] are the way your brain remembers ideas,” he said.

Although Mr. Arvai has a degree in human-computer interaction, he said he and his two co-founders didn’t understand much about brains when Prezi started. But they noticed that the software was being adopted, with no marketing, “beyond our wildest expectations,” and they started talking to scientists and user interface designers and others in similar fields to try to understand why.

One of the most surprising things they found, he said, was that people who compete in memory championships use the same technique that Prezi enables, mentally placing their ideas in a room and walking through it to recall them.

“It’s a method of loci, which is Latin for ‘place,’” Mr. Arvai said.

Although Prezi hasn’t spent the money it raised previously—about $15.5 million—it has lots of uses for its money now. The company wants users to be able to collaborate and tell stories regardless of their location or their device or their device’s screen size. It also plans to expand beyond its current 250 employees. Prezi, whose name is Hungarian for “presentation,” is now based in San Francisco.

“We still have way too many ideas that we’ve not had the opportunity to bring to market,” he said.

As part of the new funding, Spectrum Equity Managing Director Victor Parker joins the board. Mr. Arvai said Prezi chose Spectrum because the investor specializes in subscription-based businesses like Prezi’s and has helped build other successful companies in this area, including SurveyMonkey Inc. and Ancestry.com Inc.